Mechanically lockable fastener assembly

ABSTRACT

Disclosed is a mechanically lockable fastener assembly for maintaining workpieces assembled, when an elongated bolt with threads formed along a length thereof, and substantially axially aligned rotation resisting surfaces formed along another length thereof, is mechanically assembled with a cooperating nut having a threaded portion and a compressible portion deformable into engagement with said rotation resisting surfaces of said bolt to cause the bolt and the nut of the assembly to be inseparable by untorqued unthreading.

FIELD OF THE INVENTION

The present invention relates to fasteners for holding workpiecestogether, and in particular, to fastener assemblies that aremechanically lockable, and when set, prevent inadvertent separation ofthe nut and bolt of the fastener when used in a hostile environment.

Threaded fastener assemblies consist of a nut having internal threadsfor threading onto external threads of a bolt. External surfaces of thenut accept tools such as wrenches to permit tightly joining together thefastener components and clamping therebetween one or more workpieces,such as structural components or sheets.

In some environments in which workpieces are held together by fasteners,the fasteners must have extremely high integrity and strength. Further,the fasteners must bear loads not only along their longitudinal axes,but radially of such axes, also. During hostile environment operations,loads are generated varying in direction, frequency, and force, as wellas expansion and/or contraction due to temperature excursions. Fastenerspassing through the sheets become loaded in shear during theirresistance to the type of loading when one sheet tends to slide overanother. Axial loads on the fastener arise due to the clamping offastened sheets between a head of the bolt on one side of the sheets,and the nut on the other side of the sheets. Variations in the loads canweaken the fastener and cause potential separation.

A desirable feature of a fastener assembly is that the nut and bolt notcome apart or separate during use. Many systems have been suggested inattempts to prevent such separation, but usually have been determined tobe inadequate in extremely hostile environments. Typically, whenfasteners are used to retain together structures, such as components ofaircraft, which are affected by variable and continuing vibrations andchangeable forces as caused by jet engines, fastener separation canoccur after considerable operation. Upon separation, a nut or bolt whenused for example to attach components in the intake path of a jetengine, may be ingested into the engine causing loss of that engine, andpossibly loss of the aircraft as well. For such reasons, fasteners mustbe thoroughly checked periodically to retighten and/or replace anyfasteners showing separation and/or weakness. A fastener assembly of thepresent invention will not eliminate periodic inspections, but willincrease the interval between inspections as to fastener effectiveness.

    ______________________________________                                        PRIOR ART STATEMENT                                                           U.S. Pat. No.                                                                              Name           Filing Date                                       ______________________________________                                        2,396,661    P. B. Keller et al                                                                           Jan. 15, 1944                                     2,542,376    H. B. Torresen Aug. 9, 1944                                      3,290,982    C. F. Marschner                                                                              Mar. 20, 1964                                     3,418,012    J. La Torre    Oct. 17, 1966                                     3,645,125    F. A. Summerlin                                                                              Feb. 29, 1972                                     3,699,637    F. C. Roslek   Oct. 24, 1972                                     4,097,168    P. V. Pagel    Jun. 27, 1978                                     4,233,879    J. A. Sigmund  Nov. 18, 1980                                     4,260,005    E. L. Stencel  Apr. 7, 1981                                      4,370,098    F. S. Briles   Jan. 25, 1983                                     ______________________________________                                    

DESCRIPTION OF THE PRIOR ART

One proposed manner of locking a nut and bolt is to deform the threadsof the nut so that they bear inwardly in radial compression against thethreads of the bolt. Typical of these devices is described in U.S. Pat.No. 4,260,005 to E. L. Stencel, in which the resistance to unthreadingis purely frictional. The pin in this self-locking fastener system isprovided with screw threads, the lower of which are broken to permitmaterial of the nut to be deformed into the breaks or removed portionsof the threads. Although the nut or collar is deformed duringmanufacture, vibration during engine operation can cause sufficientminute rotations of the nut relative to the bolt to enable eventualseparation as the threads cut through the deformed nut material betweenthe threads.

U.S. Pat. No. 4,370,081 to Briles describes a bolt having a threadedportion remote from the head thereof. A bare portion and alongitudinally grooved portion are arranged intermediate the threadedportion and the head portion. The threaded and grooved portions of thebolt are severed from the fastener portion thereof following assembly,and are thereafter destroyed. Thus, this bolt portion does not functionas a part of the fastener assembly when the fastener portions bringworkpieces together.

In U.S. Pat. No. 3,699,637 to Roslek is shown a locking fastener systemwith the bolt attached to the workpieces by staking. The patent employsa bolt or pin that has axial grooves spaced around the outside thereof.The bolt is pressed into a workpiece, and forced therein in frictionalengagement prior to staking of a portion of the workpiece about thebolt. The threaded portion of the bolt does not effectively cooperatewith a nut or the workpiece during assembly.

Some known fasteners for use in "hostile" environments and in highlystressed assemblies are installed in interference fit with alignedopenings in abutting components. A specific example of such fasteners isshown in U.S. Pat. No. 4,097,168 to Pagel. In this patent, the nutengages only the threads of the bolt to pull the tapered shank of thebolt into a predrilled hole causing plastic flow of material into lobesalong the shank of the bolt.

In U.S. Pat. No. 3,418,012 to LaTorre, a nut is threaded onto a threadedportion of a bolt to stress the material between the head of the boltand the nut. The shank of the fluted bolt is in interference fit in theexact size, tapered hole of the workpieces for prestressing theworkpieces connected thereby upon threading of the nut on the bolt.

In neither of these patented constructions is the nut swaged to the boltso as to preclude inadvertent unthreading of the nut from the bolt, andpossible separation of the workpieces.

In still other patents, such as U.S. Pat. No. 3,290,982 to Marschner,the nut is swaged onto the bolt by axial movement of a chamfered anvilwhich causes cold flow or swaging movement of material of the nut intothreads of the bolt. Following assembly, the portion of the bolt onwhich the swaging tool is mounted is broken away.

U.S. Pat. No. 2,396,661 to Keller et al and U.S. Pat. No. 2,542,376 toTorresen disclose a securing device for attaching workpieces together byswaging a malleable collar about a pin to form a composite rivet. Thepin is provided with several annular teeth defining groovestherebetween. Material of the collar is forced into the grooves byapplying axial pressure from a setting tool. The setting of the fastenerassembly, according to these patents, relies on the interior shape ofthe tool and the significant axial force which must be applied by thetool against the nut.

U.S. Pat. No. 3,645,125 to Summerlin describes a lockbolt swagingapparatus having a nut swaged on a pin in a manner similar to that ofKeller et al. The pin is provided with a threaded portion which isremoved from the lockbolt after assembly, therefore not providing thesubstantial attaching means generated by the mechanically mated andthreaded portions of the present invention.

U.S. Pat. No. 4,233,897 to Sigmund describes a grooved fastener whichincludes an unthreaded bolt member having two groups of grooves formedtherein, with the depth of each group being the same. A collar is swagedonto the bolt.

The prior art patents approach the problem of a fastening system for usein hostile environmental conditions in many ways. However, none describea concept having the permanence of assembly as the assembly of thepresent invention. None describe the combination of a bolt of a fastenerassembly having a substantially axially aligned rotation resistingsurface formed along the shank of the bolt interiorly of a threadedportion, to which a nut, during assembly, is deformed compressively intospline-like portions for engaging the rotation resisting surfaces of thebolt, and being incapable of unthreading over the threaded portion ofthe bolt, whereby the assembly is made inseparable by untorquedrotational forces.

SUMMARY OF THE INVENTION

The present invention provides a unique fastener assembly, and a toolfor mechanically locking the nut of the assembly to the bolt thereof,sufficiently to preclude inadvertent separation of the fastenerassembly.

In the invention, the bolt of the fastener assembly is provided with asubstantially axially oriented rotation resisting knurled surfaceportion forming shank radius elevations or splines internally of andcontiguous with a threaded portion of the bolt. The nut of the fastenerassembly is provided with a threaded portion, and a non-threaded portionof an internal diameter corresponding to the maximum diameter of thethread of the bolt with which it is to be used. After threading the nutonto the bolt, the nut is swaged or compressed mechanically so that someof the material of the non-threaded portion thereof is deformed into therotation resisting surface portion of the bolt. Because of thedeformation of the nut into the axially aligned grooves of the knurledsurface, the nut cannot be vibrated loose from the bolt. Hostileenvironments are unable to establish sufficient twisting and/or axialtorque to cause the deformed portion of the nut to move axially over thethreaded portion of the bolt, and/or the threaded portion of the bolt tocut a groove into the axially deformed portion of the nut.

A driver or other deforming tool functions both to thread the nut ontothe bolt of the fastener assembly, and to perform the compression actionon the nut. Such a driver tool, powered by a rotary drive, providesrotation of the nut onto the bolt to bring together workpiecestherebetween to a specified torque, and thereafter to initiate aninwardly operative compression or swaging force about the nut to swageor otherwise compress a portion of the nut onto the bolt to precludeinadvertent or environmentally induced separation of the fastenerassembly. The socket-like tool, with its swaging inserts, engages acompressible portion of the nut and applies thereto an inwardly radialor compressive force to mechanically displace the selected portions ofthe nut into spline-like portions of a depth permitted by the minimumradius of the shank portion of the bolt. The compressed nut material,when mechanically deformed into the shank portion of the bolt, createssignificant resistance to rotation and/or axial movement of the nut onthe bolt, thereby precluding unthreading of the assembly. Thus, thefastener assembly together with the workpieces are maintained securewhen subjected to hostile environmental conditions.

Among the several advantages of the fastener assembly of the presentinvention, the mechanical locking procedure provides a more effectivelock arrangement than prior art fastener assemblies. Specifically, bylocating the locking portion internally of the threaded portion of theassembly, greater resistance to unthreading is provided than isoccasioned with fastener assemblies having the threaded portion internalof the locking portion. The threads of prior art assemblies canestablish a thread pattern due to vibration, shock, andexpansion/contraction due to temperature excursions, which in time canenable unthreading and possible separation to occur. In contrast, theinternally arranged splines of deformed nut material of the presentinvention cause individual splines to establish resistance againstunthreading rotation both as each spline is encountered by a cooperatinggroove of the bolt, and thereafter by the threads as each new portion ofa spline is encountered thereby. Thus, in addition to the highresistance to rotation established by the splines of the nut relative tothe complimentary knurled grooves of the bolt, further rotationalresistance occurs as any rotation and/or axial movement of the nutoccurs. Therefore, the resulting fastener assembly provides for alocking arrangement of greater permanence than comparably dimensionedfastener assemblies of the prior art, when used in equally hostileenvironment conditions.

OBJECTS OF THE INVENTION

An object of the present invention is to provide a mechanically lockableworkpiece fastener assembly which will not separate during operation ina "hostile" environment.

Another object is to provide a threaded fastener assembly including amechanical interlock restraint against separation internal of thethreaded portion of the assembly.

Still another object is to provide a fastener assembly including a nutand bolt combination on which the nut is compressively deformed onto arotation resisting knurled surface portion of the bolt, which portion isinternal of the threaded portion of the bolt.

The above and other objects of the invention will be better understoodby referring to the following description taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational view of a preferred embodiment of a fastenerassembly with workpieces assembled, and with portions broken away forclarity.

FIG. 2 is a perspective view of a tool for swaging the fastenerassembly, with portions broken away for clarity.

FIGS. 3A, 3B, and 3C are cross-sectional views of a fastener assemblytaken on section line 3A, B, C--3A, B, C of FIG. 1, showing the assemblyboth before and after swaging of the nut on the bolt of the assembly,and including a swaging tool in operative position.

FIG. 4 is a perspective view of an alternate embodiment of a tool forswaging the fastener assembly, with portions broken away for clarity.

FIGS. 5 and 6 are perspective views of other embodiments of a fastenerassembly of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The novel fastener assembly is usable for fastening together workpiecesor components of structures which are to be used under "hostile"environmental conditions. Typically, the fastener assemblies may be usedto join together components of high fatigue rated structures, which maybe the sheets or skins of aircraft and other components, some of whichmay be used in air inlets for jet engines. Vibrations of varyingfrequency and amplitude over extended time intervals, and expansionand/or contractions due to significant temperature excursions create thehostile environmental conditions capable of causing separation of moreconventional fastener assemblies. If the structures separate, and/or thenut comes apart from the bolt, such separation may permit the nut or aportion of the assembly to become ingested into the machine or engine inwhich it is used, resulting in damage to or destruction of the machineor engine. If the engine is used in an aircraft, the ultimate damage maybe loss of the aircraft.

As shown in FIG. 1, a fastener assembly 10 is illustrated as comprisinga bolt 20 and a nut 40 which together maintain assembled at least twoworkpieces 60, shown as sections of sheets of material to be heldtogether, such as aircraft skins.

The dimensions of the components of the fastener assembly are selectedaccording to the strength requirements needed to bring together theworkpieces 60, and to hold them secure, as shown in FIG. 1. The diameterdimension of the bolt 20 is configured to be adequate for the materialselected therefor to have sufficient strength to withstand shear forcesgenerated thereon by the workpieces 60, and to withstand axial forces ofthe nut 40 when assembled thereon to retain the workpieces together. Thelength dimension of the bolt 20 is selected to enable secure mating ofthe nut 40 on the bolt 20 when the workpieces 60 are in position.

The bolt 20 has a head portion 22 which may be flush externally with thecorresponding surface of the workpiece, or may be designed to extendeither above or below the workpiece surfaces, as desired. Typically, thehead portion 22 of the bolt 20 may be provided with a retainer or driverrecess or slot 24, and/or the other end may be provided with a similarretainer or driver access, as shown at 25. Such a recess or slot 24and/or retainer 25 is known to be used to enable the bolt to berestrained in position during assembly or threading thereon of the nut40.

Below the head of the bolt 20, and extending substantiallylongitudinally thereof are a plurality of nut rotation resistingsurfaces, shown as locking grooves or knurled portions 26. These knurledsurfaces 26 may be spaced equally or unequally about the periphery ofthe bolt. The knurled surfaces formed about the bolt extend along aportion of the length of the bolt configured according to the desiredstrength of the fastener assembly, and/or the thickness dimension of theworkpieces 60. These nut rotation resisting surfaces are spaced from thelead portion by a relatively small shank portion 28.

Another portion of the length of the bolt 20 is provided with threads 32of a depth and pitch, as required to provide for adequate retention ofthe nut 40 thereon in the manner of a more conventional nut and boltassembly. In this preferred embodiment, the threaded portion 32 isproximate the end of the bolt opposite the head relative to the knurledportion thereof of which is intermediately the head and threadedportions.

The nut 40 is of a length sufficient to engage the threaded portion 32and at least a portion of the knurled surfaces 26 of the bolt 20, suchthat the nut can be assembled on the bolt with workpieces 60 between thehead 22 of the bolt and a head portion 42 of the nut. The internallythreaded portion 44 of the nut 40 is configured complimentary to thethreads of the cooperating bolt 20.

Intermediate the head 42 and threaded portions 44 of the nut 40, acompressible portion 46 is formed externally with socket engageablesurfaces, shown as chords or flats 48 in FIG. 3A, and concave surfaces48a in FIG. 3C. These surfaces come together at junctions or apices 52.Internally, the compressible portion 46 of the nut is of a diameter topermit longitudinal movement thereof over the threaded portion 32 of thebolt, during initial assembly. The dimensions of the compressibleportion 46 of the bolt, specifically the height of the apex junctions52, are selected so that the rotational force applied thereto willtorque the nut onto the bolt to a predetermined torque before swaging ofthe nut begins.

In a typical assembly, workpieces 60 are retained between the proximatesurfaces of the head 22 of the bolt 20 and the head 42 of the nut 40.After tightening of the nut to the desired torque on the bolt, some ofthe material of the nut is displaced into the grooves of the compressionarea 26 of the bolt, as shown in FIG. 3B. The displacement of thematerial by compression or swaging is obtained by a tool, such as thetool 80 as shown in FIGS. 2, 3 and 4.

In a preferred embodiment of the tool 80, as shown in FIG. 2, the toolhas a substantially hollow socket or nut engaging portion 82, and adriver engageable portion 84 defining the opposite end thereof.Intermediate the ends of the socket, and partially recessed within thewall 86 of the socket 80 are swaging inserts 90, which extend slightlyinwardly of the interior of the socket. The length and radius dimensionsof the tool are selected to provide efficient functioning with the nutand bolt of a fastener assembly 10 having pre-selected dimensions. Thatis, the socket portion 82 of the tool is configured to a length torecess over a portion of the bolt 20 and a portion of the nut 40 whenthreaded onto and fixed to the bolt. Similarly, the internal radialdimension of the socket-like tool 80 is selected to be a slightlygreater radius than the external central radius of the driver engagingsurfaces 48 of the nut to be operated on thereby, yet to approach theminimum radii of the apex junctures 52 between the surfaces 48. Theresulting configuration of the nut enables threading of the nut onto thebolt in the manner of a conventional fastener assembly, until the nutand workpieces are tightened one against the other.

The swaging inserts 90 in the tool 80 are formed of material selected tohave a hardness factor greater than that of the material of the nut 40.These inserts, preferably of cylindrical shape, may be dimensioned to alength greater than, substantially equal to, or less than the length ofthe desired compression area of the nut. The inserts may be assembled inthe tool 80 against any movement, but are preferably rotatable in seats92 formed in the socket wall 86. Following location of the inserts 90within the seats 92, a retainer sleeve (not shown) may be positionedover bearing ends or portions of the inserts to retain the same inposition when a nut is not loaded therein. Alternatively, a portion ofthe internal wall may be swaged or otherwise formed over portions of theinserts as necessary to preclude disengagement of the inserts from thesocket 80.

Variations of the nut configuration are shown in FIGS. 3A and 3C. Theapices or junctions 52 between the driver engaging surfaces or flats 48of the nut 40 may be aligned with or positioned between the knurledportions or grooves 26, 26a of the bolt 20. The swaging causesdisplacement of the quantity of material in the area 62 of the nut intothe grooves of the bolt. That is, the material of the nut beyond theradius as defined by the central radius of flats 48 is forced inwardlyin a substantially radial manner.

Following insertion of a bolt 20 through prepared bores in workpieces60, a nut 40 is mated with the driveable socket 80. Some of the externaldriver engaging surfaces 48 of the nut are aligned with correspondingswaging inserts 90 in the socket. Upon rotation of the socket tool 80,the nut 40 is threaded onto the bolt 20 until the head portion 42 of thenut tightens the workpieces 60 against one another and the internalportion of the head 22 of the bolt. Continued rotation of the socket 80causes the swaging inserts 90 of the tool 80 to apply inwardly radialforce to the surface portions of the nut at a radius greater than theminimum radius of surfaces 48. This causes material at the compressionarea 46 of the nut 40 to be displaced, and compressed or swaged into thegrooves 26 of the bolt 20. Such compression occurs as the swaginginserts move from the flats 48 of the nut 40 over the apex junctions 52,thereby reducing the external diameter of the compression area of thenut to a dimension substantially corresponding to the internal radiusdefined by inserts 90, and the radius at the center of the flats 48 ofthe nut. Since the mechanical force displaces or pushes material of theswaged portion of the nut inwardly in a substantially radial manner, thefinal external diameter of the nut will not exceed the maximum internaldiameter of the swaging inserts 90. Upon completion of the swaging ofthe nut, the socket tool 80 will rotate freely about the nut until thetool is withdrawn or rotation thereof is stopped. The swaging action isaccomplished solely by rotational action on the nut thereby avoidingdistortion of the workpieces which might be caused by axial swagingaction.

Although in the preferred embodiment of the fastener assembly 10 in FIG.1, the compression area 46 of the nut 40 is of a length less than thatof the axially grooved or knurled area 26 of the bolt 20, thecompression area may be extended to engage a selected portion of thethreaded area 32 of the bolt, as well as a portion of the shank 28 ofthe bolt 20.

Another embodiment of the socket tool is shown in FIG. 4. In this tool80', the swaging inserts 90' are formed as spheres, or balls recessedpartially in seats in the wall 86' of the socket. These balls may bealigned equal distances from a longitudinal datum line of the tool, ormay be aligned at different longitudinal distances t, so as toindividually engage the nut 40 in different tracks along the compressionarea 46 thereof. The balls in these tracks, whether equally or unequallyspaced circumferentially, adequately swage the nut onto the bolt topreclude separation of the fastener assembly.

In FIG. 3C is illustrated a modification of the nut 40 on which thesocket engaging surfaces, shown previously as chords or flats 48, arereplaced by slightly concave surfaces 48a. With this embodiment of thenut, a socket 80 can be selected having an inner diameter correspondingto the least diameter of the nut, i.e. the diameter formed by thebottoms of the concave surfaces 48a. As can be appreciated from acomparison of material displaceable from area 62 in FIG. 3A, and thematerial displaceable from area 62a in FIG. 3C, a greater quantity ofmaterial is seen to be displaced in the latter configuration. The areasare compared in that the depth of the area at 62 is the depth shown at"r" in FIG. 3A, whereas the depth at area 62a is the depth "r" plus theadditional depth from the chord to the bottom of the concave surface48a. Since the depth of the substantially triangular area at 62a isgreater than that at 62, but the separation between apices 52 isunchanged, the base of the area is extended as well.

The greater quantity of displaced material in FIG. 3C therefore providesfor somewhat greater compression of material into the grooves of knurledportions 26 of the bolt 20. By increasing the area 62 defining thequantity of material to be displaced, a higher torque level must occurduring threading of the nut 40 on the bolt 20 before swaging of the nutwill be initiated. Thus, the swaging action required for compressing ofmaterial of the nut on the bolt is increased, providing for enhancedretention of the components of the fastener assembly.

Another embodiment of a bolt of the fastener assembly is shown in FIG.5. The bolt 20' is configured so that the shank diameter ribs of theknurled portion 26' thereon are not parallel one with another. By thisconfiguration, after the nut 40 is assembled and material thereof iscompressed into the grooves or around the ribs of the knurled portion ofthe bolt, the nut is incapable of axial or rotational movement relativeto the bolt.

In another embodiment of the bolt 20" as shown in FIG. 6, the lockingknurled portion 26" may be inclined slightly relative to thelongitudinal axis of the bolt. Ideally, the direction of inclination isopposite to the nut unthreading direction to cause the deformed materialof the nut to wedge against the radial walls of the bolt forming theknurled portion, and further preclude inadvertent unthreading of the nut40 from the bolt 20.

The nut rotation resisting portion 26 of the bolt is arranged internallyof the threaded portion of the bolt to provide greater lockingpermanence than is available with known prior art designs. By thepresent arrangement, the nut fixed on the locking portion 26 isincapable of rotation due to the spline-like deformation of materialthereof in the grooves of the bolt. No threads or threaded portions areavailable to establish the necessary rotational track for unthreading ofthe nut. Further, should any axial displacement of the nut on the boltoccur, the spline formed by nut material extending longitudinally of thebolt will resist cutting action of threads 32 of the bolt. That is, eachspline of the nut complimentary to a groove will establish significantrotational resistance on each occasion when a thread is encountered.Also, any loosening action of the nut on the bolt will cause fresh ridgeportions to further wedge against the threads. Thus, the possibility ofa continuous thread being formed on the nut for unthreading engagementwith respect to the threaded portion 32 of the bolt is substantiallynil.

In view of the configuration of the fastener assembly 10, the nut 40cannot move into tighter engagement with the workpiece 60, and cannotmove away from the workpiece. Due to wedging action of the deformedmaterial of the nut into the grooves of the bolt 20, significant torque,in excess of the untorqued forces caused by vibrations, shocks, andtemperature excursions that occur during normal operating conditions,must be applied for disassembly.

It is further understood that variations and modifications of thepresent invention which lie within the scope of the appended claims arefully contemplated.

I claim:
 1. A non-removable fastener assembly for passing through holesin workpieces comprisinga bolt, a nut, and a driving tool, said bolthaving a head at one end and a shaft extending from the head andthreaded over a portion of its length, said nut having a head end and athreaded bore therethrough for engaging the threaded part of the boltshaft, said bolt and nut being constructed and arranged for clampingworkpieces tightly together permanently under a predetermined a clamp upload when the nut is driven by the tool, said bolt shaft having a firstportion thereof next to said head for passing through the workpieces, asecond portion which is unthreaded, and a third threaded portionextending from the second portion to the end of the shaft respectively,means for forming a plurality of generally axial rotation resistingrecesses arranged around the circumference of the shaft and along thesecond portion, said nut having a first interior portion of axial lengthapproximately the same as the second portion of the bolt shaft andhaving no threads therein so that said unthreaded first interior portionof the nut and said unthreaded second portion of the bolt shaft do notthreadedly engage each other, said nut having a second interior portionwhich is threaded for engaging the third threaded portion of the boltshaft, said nut further having a first exterior portion adjacent at thehead end thereof and extending the same axial length along said nut asthe second interior unthreaded portion of the shaft, said nut firstexterior portion being polygonal in cross section, and a second exteriorportion extending from the first portion to the other end of the nut,said said second portion having a cross section smaller than said firstnut exterior portion, said nut being constructed for being driven up tospecification load and thereafter swaged into intimate contact with therecesses of the bolt shaft by a nut driver, said nut driver having abore therein for accepting the nut, said bore having a first sectionextending from one end the same axial length as the first exteriorportion of the nut and having an internal cross section larger than thenut, and a second section extending from the first section inwardly,said second section being circularly cylindrical and larger than thesecond section of the nut so as not to engage the same, swaging meansembedded in the sidewall of the interior of the driver first section forengaging at least two faces of the first exterior portion of the nut sothat the driver can take up on the bolt shaft until the respectivethreaded portions and shaft are cooperatively and fully engaged and thenut abuts and clamps the workpiece with said predetermined force,thereafter further turning of the driver deforms the material of thefirst section of the nut into the grooves of the second section of theshaft of the bolt, continuing turning of the driver causing the swagingmeans to deform each of the nut apexes in turn until the driver turnsfreely and can be thereafter removed for reuse, said driver rotationalmotion being the sole mechanism for taking up the nut to specificationtightness and for deforming the nut securely into the bolt shaft.
 2. Aremovable fastener system for passing through holes in workpiecescomprisinga bolt having a head at one end and a shaft extending from thehead and threaded over a portion of its length, a nut having a head endand a threaded bore therethrough for engaging the threaded part of thebolt shaft, said bolt and nut being constructed and arranged forclamping workpieces tightly together permanently under a predetermined aclamp-up load when the nut is taken up on the bolt, said bolt shafthaving a first portion thereof next to said head for passing through theworkpieces, a second portion which is unthreaded, and a third threadedportion extending from the second portion to the end of the shaftrespectively, said bolt shaft further formed with a plurality ofgenerally axial rotation resisting recesses arranged around thecircumference of the bolt shaft and along the second portion, said nuthaving a first interior portion of axial length approximately the sameas the second portion of the bolt shaft and having no threads therein sothat said unthreaded first interior portion of the nut and saidunthreaded second portion of the bolt shaft do not threadedly engageeach other, said nut having a second interior portion which is threadedfor engaging the third threaded portion of the bolt shaft, said nutfurther having a first exterior portion adjacent the head end thereofand extending the same axial length along said nut as the secondinterior unthreaded portion of the bolt shaft, said nut first exteriorportion having driver engaging surfaces including a flat and apexes, anda second exterior portion extending from the first portion to the otherend of the nut, said second portion having a cross section smaller thansaid first nut exterior portion, whereby said bolt and nut can be takenup to specification by a rotatable nut driver having swaging meansembedded in the sidewall thereof for engaging the flat of the firstexterior portion of the nut so that the driver can take up the nut onthe bolt shaft until the respective threaded portions and shaft arecooperatively and fully engaged and the nut abuts and clamps theworkpiece to the bolt head with said predetermined force, thereafterfurther turning of the driver causes the swaging means to deform andswage the material of the first section of the nut into the recesses ofthe second section of the shaft of the bolt, and continuing turning ofthe driver causing the swaging means to deform each of the nut apexes inturn until the driver turns freely and can be thereafter removed forreuse, said driver rotational motion being the sole mechanism for takingup the nut to specification tightness and for deforming the nut into thebolt shaft to secure the same.
 3. A removable fastener system forpassing through holes in workpieces comprisinga bolt having a head atone end and a shaft extending from the head and threaded over a portionof its length, a nut having a head end and a threaded bore therethroughfor engaging the threaded part of the bolt shaft, said bolt and nutbeing constructed and arranged for clamping workpieces tightly togetherpermanently under a predetermined a clamp-up load when the nut is takenup on the bolt, said bolt shaft having a first portion thereof next tosaid head for passing through the workpieces, a second portion which isunthreaded, and a third threaded portion extending from the secondportion to the end of the shaft respectively, means for forming aplurality of generally axial rotation resisting recesses arranged aroundthe circumference of the bolt shaft and along the second portion, saidnut having a first interior portion of axial length approximately thesame as the second portion of the bolt shaft and having no threadstherein so that said unthreaded first interior portion of the nut andsaid unthreaded second portion of the bolt shaft do not threadedlyengage each other, said nut having a second interior portion which isthreaded for engaging the third threaded portion of the bolt shaft, saidnut further having a first exterior portion adjacent the head endthereof and extending the same axial length along said nut as the secondinterior unthreaded portion of the bolt shaft, said nut first exteriorportion having driver engaging surfaces including a flat, and a secondexterior portion extending from the first portion to the other end ofthe nut, said second portion having a cross section smaller than saidfirst nut exterior portion, said bolt and nut being thereby constructedand arranged to be taken up to specification by a rotatable nut driverhaving a bore therein for accepting the nut, said bore having a firstsection extending from one end the same axial length as the firstexterior portion of the nut and having an internal cross section largerthan the nut, said driver further having swaging means embedded in thesidewall of the first section of its bore for engaging the flat of thefirst exterior portion of the nut so that the driver can take up the nuton the bolt shaft until the respective threaded portions and shaft arecooperatively and fully engaged and the nut abuts and clamps theworkpiece to the bolt head with said predetermined force, thereafterfurther turning of the driver causes the swaging means to deform andswage the material of the first section of the nut into the recesses ofthe second section of the shaft of the bolt, and continuing turning ofthe driver causing the swaging means to deform each of the nut apexes inturn until the driver turns freely and can be thereafter removed forreuse, said driver rotational motion being the sole mechanism for takingup the nut to specification tightness and for deforming the nut into thebolt shaft to secure the same.
 4. A fastener assembly as in claim 3wherein the rotation resisting recesses of said bolt are oriented at aslight angle relative the longitudinal axis of said bolt.
 5. A fastenerassembly as in claim 3 wherein the rotation resisting recesses of saidbolt are oriented at a slight angle opposite to the direction of theunthreading action of the nut relative to the bolt.
 6. A fastenerassembly as in claim 3 wherein said bolt is provided with a ledgeportion joining said threaded and said rotation resisting recesses.
 7. Afastener assembly as in claim 3 wherein the compression portion of saidnut is of greater length than the rotation resisting recesses of saidcooperating bolt to enable compression of said nut onto at least a partof said threaded portion of said bolt.
 8. A fastener assembly as inclaim 3 wherein the rotation resisting recesses comprises a plurality ofgrooves.
 9. A fastener assembly as in claim 3 wherein the rotationresisting recesses is of a knurled configuration having discontinuancesextending substantially longitudinally of said bolt.
 10. A fastenerassembly as in claim 3 wherein the rotation resisting recesses along thesecond length of said bolt are oriented in a direction substantiallyopposite to the direction of the threads of the bolt, to preventunthreading action of the nut relative to the bolt.
 11. A fastenerassembly as in claim 3 wherein the rotation resisting recesses of saidbolt are not parallel one with another whereby the rotation resistingsurfaces are configured to prevent axial displacement of material of anut when the material is deformed into the rotation resisting surfacesupon compression of said nut.
 12. A fastener system as in claim 3wherein said driver engaging surfaces are flat of a polygon.
 13. Afastener assembly as in claim 3 wherein said driver engaging surfacesare concave whereby a greater quantity of nut material is displaceableinto said rotation resisting recesses of said bolt than when said driverengaging surfaces of said nut are defined as chords extending betweenapices spaced about said nut.